Added the preview branch to the list of branches for docker-publish

Author: bmispelon

.github/workflows/docker-publish.yml

@@ -2,7 +2,7 @@ name: Create and publish a Docker image
 
 on:
     push:
-        branches: ["main"]
+        branches: ["main", "preview"]
 
 env:
     REGISTRY: ghcr.io